In a rotor of a motor rotor used in an electric compressor, multiple magnetic steel sheets are cylindrically laminated so as to configure a rotor core, a magnet is embedded to the inside of the rotor core, end plates are laminated on both ends of the rotor core, balance weights are laminated on both end surfaces, and the rotor core, the end plates, and the balance weights are integrally fastened by multiple headed swage pins which are inserted from one side (for example, refer to PTLs 1 and 2).
In this motor rotor, in general, a ferrous base material is used as the material of the swage pin, and a brass material, a zinc material, a stainless material, or the like is used as the material of the end plate in order to prevent a leakage of magnetic flux. In addition, a brass material, a zinc material, a stainless material, or the like which is a metal having a high specific weight is used as the material of the balance weight. In addition, in order to integrally fasten multiple magnetic steel sheets including balance weights and the end plates, bolts shown in PTL 3 are used. However, economically, as shown in PTLs 1 and 2, the end plates and/or balance weights are integrally fastened simultaneously by the swage pins.